Photo examples of aborted pinheads and mushroom aborts. Usually, such shrooms and pins stop growing, and mushroom caps turn black or dark-blue. Caused by stress, poor environmental conditions, genetic issues. It's not a contamination!
If you find your pins and mushrooms have stalled, stopped growing and their caps turned black
If you find Overlay and Stroma symptoms: cottony, cloudy, mat-like or crust-like dense mycelium. Contamination or not? Why overlay appear? Is it possible to fix overlay and stroma?